STATE ^ANT BOARD
United States Department of Agriculture
Agricultural Research Administration
Bureau of Entomology and Plant Quarantine
EVALUATION OF FUMIGANTS FOR SHELLED CORN"
By L. M. Redlinger, B. R. Wilson,-' R. T. Cotton, and H. H. Walkden
Division of Stored Product Insect Investigations
The Government grain-loan program authorized by the Agricultural
Adjustment Act of 1938 led to the holding of large quantities of shelled
corn in farm-type storage structures. At first conventional round gal-
vanized-metal bins were used mostly, but later many types of wooden
and metal bins, quonsets, and warehouses came into use.
When the bins were new, the only insects found in them were species
that had been carried in with insufficiently cleaned corn or that had
reached the bins by flight. Infestations found during the first few years
consisted almost entirely of grain beetles, the immature stages of which
are free living. Recently, however, there has been an increase in
weevils, the grubs of which feed inside the corn kernels. In some States
more than one-third of the bins contain weevil infestations. This change
in the insect population with its increase of forms more resistant to
fumigants, together with the new types of storage structures, has neces-
sitated continued research to develop more effective fumigants and
Early in the program a 75-25 mixture of ethylene dichloride and
carbon tetrachloride was adopted as the standard fumigant for shelled
corn in steel bins for application at a dosage of 6 gallons per 1,000
bushels. Later an 80-20 mixture of carbon tetrachloride and carbon
disulfide at 5 gallons per 1,000 bushels came into favor and largely
replaced the one containing ethylene dichloride.
Many failures were reported with these fumigants, but usually they
could be accounted for by the presence of excessive amounts of caked
and damp grain on the surface or throughout the bin and also by the
large amounts of dockage. Occasionally incomplete kills appeared to
be associated with outbreaks of the Angoumois grain moth.
Some of the tests made with old and new fumigants under varying
conditions and in various types of structures are reported herein.
1/ A portion of the tests reported herein were made in cooperation
with the Grain Branch of the Production and Marketing Administration.
2/ Resigned April 13, 1951.
:• :. .. J'
nat the full I ant
bin. In some tests an ad aJ sample was
ill free-living forms, and tl held for possible
• of weevils ths. The living and dead ins*
avera tsis of a 1,000-gram samp
Tests with 80-20 Mixti.
The 80-20 mixture of carbon tetrachloride and carbon disulfide
i.'d under many conditions and in all types of storage structures. In
:ieral, a dos. 5 gallons per 1,000 bus* found to be adequate
•he treatment of clean, dry, sheik- '-el
bins and for the spot treatment of isolated infestations in quonsets or
similar lar ge storage structures. I "h mu
th( surface or large ami *age and caked corn through-
out the bin, this ige was inadequ. Before fu on it was n«
essary to remove all caked and mo. surface and turn
and i rider of the bin.
In wooden rectangular bins o , drj rn, a dosa* Ions
1,000 bushels was founc isa ive results.
ta with I
and in a mixture with other ran
bins of shell n, i he corn a
irfac( is hot,
vith bi ties. In prepi >r fun
CI rinkli ; a
wa ! m JU1 al
of chloropicrin in 1 gallon of (1) carbon tetrachloride, (2) the 80-20
mixture of carbon tetrachloride and carbon disulfide, or (3) the 75-25
mixture of ethylene dichloride and carbon tetrachloride. All mixtures
were sprayed over the surface of the grain.
Chloropicrin in admixture with carbon tetrachloride was tested at
dosages of 1, 1 l/2, and 2 gallons per 1,000 bushels. The results were
much better than with the chloropicrin alone, but even with the 2-gallon
dosage a complete kill was not obtained.
Chloropicrin with the 80-20 mixture in dosages up to 1 1/2 gallons
and with the 75-25 mixture in dosages up to 2 gallons per 1,000 bushels
failed to give complete kills.
The results of these tests are given in table 1. In the first three
treatments with chloropicrin alone and the first two with the chloropicrin-
carbon tetrachloride mixture, the average number of insects per 1,000-
gram sample was computed from two bins. All the other averages are
on the basis of one bin only.
Table 1. --Effectiveness of chloropicrin and chloropicrin mixtures in the
fumigation of shelled corn in steel bins, 1950
Average number of
insects per 1,000-
Chloropicrin 2 lb. in 1 gal. of-
9 of the standard 80-20 and
nail quantities of a more toxic n.
>f methyl bron ts
>f these- mixtures. In the first tests with the
•it of sulfur dioxide was also added as a warning gas.
,200-bushel metal bins of shellec:
r of damp, d mol
grain at th< Air temperatures ranged from 50° to . and
50° to 9
for the fun n the caked surface gra -n
with shovels. Three replications of both mixtu; -*re mad«
•id 3 gallons per 1,000 bushels. <> fumigant was applied
ov surfa* ijrain with a pump that delivered 2 gallons p-
>ken 1 week after fun in sho it a n< om-
kill ha led in all bii th both mixtures th dosages.
In three of the twelve bins a single live insect was found in ice
ts, undertaken in wa fumigai ted
that some i aked gra.
lin was removed befoi
this troul ne (table
lion dosage of
Suppli< 1 1 pe
and I 2
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h n f
-* ^ ,h
CO rH co
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CO ^ CO
^* i— i »— t i— ( o
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cm m c~
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k had shown m n admixtur.
nide or chl< in to be promising for the fumigation
: metal bins. Such mixtures B .e
under pressure in cylinders that Lf- emptying, Tiat th>
applied from outside the bin by merely opening a valve and allowing
fumigant to flow through a tube into the grain.
ill tests with these mixtures a coil of plastic tubing i to
the cylinder was buried 6 to 8 inches 1 th the surface of the grain.
Th«- tubing extended in a complete circle about 2 feet from the walls of
n with the free end across the middle. I was plugged and
holes were bored through the tubing at 3-foot intervals. By placing the
cylinder of fumigant on a pair of scales it was possible to weigh in tl
iired amount of fumigant. The mixtures caused frequent breakages
in the tubing.
Mixtures containing methyl bromide and ethylene dibromide were
made in the following proportions by volume: 1-1, md 1
All mixtures were used at the rates of 5, and 7 1/2 pounce
n treated was in poor condition- -heavily Infe
in spots. Grain temperature.- nerally high ar;
101 • tures 7 4° to 82° and grail
- 7 -
air temperature at the time of fumigation was 75°. Dosages of 3, 5,
and 7 pounds of this mixture were applied in the same manner as the
methyl bromide-ethylene dibromide mixtures. Practically no kill of
adult insects was obtained at any dosage (table 2), although there was
little emergence of weevils from samples of grain removed after treat-
Ethylene Dibromide-Ethylene Dichloride-
Carbon Tetrachloride Mixtures
A mixture containing 7.2 percent of ethylene dibromide, 29.2 percent
of ethylene dichloride, and 63.6 percent of carbon tetrachloride (by
weight), known as EB-5 grain fumigant, was tested in steel bins at
dosages of 2, 3, and 5 gallons per 1,000 bushels. The fumigant was
applied uniformly over the surface of the corn in a coarse spray.
Probe samples taken 2 weeks after fumigation showed that an average
of one adult insect per 1,000 grams survived fumigation at both the 2-
and 3-gallon dosages, but that at the 5-gallon dosage mortality was
complete. Weevils emerged from samples of grain fumigated at the
two lower dosages, but not from samples fumigated at the 5-gallon
A mixture containing 18.3 percent of ethylene dibromide, 24.1 per-
cent of ethylene dichloride, and 57.6 percent of carbon tetrachloride was
found to be no more efficient.
1, 1-Dichloro-l-nitroethane-Carbon Tetrachloride Mixture
A mixture containing 2 pounds of 1, 1 -dichloro-1-nitroethane in 1
gallon of carbon tetrachloride (approximately 17-83 percent by volume)
was tested at dosages of 1, 2, and 3 gallons per 1,000 bushels. The
fumigant was applied in a coarse spray uniformly over the surface of
eight 3,200-bushel bins. The caked and moldy surface grain was re-
moved and the surface leveled with a rake. Grain moistures ranged
from 10.3 to 13.7 percent, grain temperatures from 72° to 94° F., and
the air temperature at the time of fumigation was 80°.
A dosage of 1 gallon per 1,000 bushels did not give a complete kill
of adult insects, but at both the 2- and 3-gallon dosages the kill was
nearly complete (table 2). No weevils emerged from grain samples
taken from the bins after fumigation.
Bromotrichloromethane-Carbon Tetrachloride Mixture
A mixture containing 10 percent of bromotrichloromethane (by
volume) and 90 percent of carbon tetrachloride was tested at 3 and 4
gallons per 1,000 bushels. It was applied as a coarse spray uniformly
over the surface of the grain in 3,200-bushel metal bins. The crusted
nun f mat'
in admixtui i
I 1 gal lor
bushel bin. d 30 ;
in f I
' per 1|
111 £\J I O
Digitized by the Internet Archive
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boom on a sled so that it could be pulled across the surface of the corn
from outside of the building while the fumigant was sprayed in a pattern
that covered the corn from one side of the building to the other (figs. 1
Figure 1.-- Sled with spray boom
mounted and connected to pump
and supply tank.
Figure 2. --Sled with spray boom
on surface of corn in quonset.
The spray boom is made of a 24-inch length of 3/4-inch gas pipe
bearing a nozzle with two 3/4-inch off-center nozzles. It is held firmly
to a horizontal support pipe by U-bolts and strap irons to make a pipe
clamp. The support pipe is of 3/4-inch gas pipe fastened by I-bolts to
the uprights of the sled, 44 inches high for quonsets 32 feet wide and
49 inches high for those 40 feet wide. This pipe can be rotated by
loosening the I-bolts. A hose-to-pipe fitting is attached to the front
end of the nozzle pipe and a 90° street L to the back end. The nozzle
is attached to the street L. The nozzle tips should be level with the
support pipe and about 12 to 15 inches back of it, with the angle between
the nozzles about 20° to 30°. The slotted disks in the nozzles should
have the wide portion to the top or outside and the slots perpendicular
or parallel to the support pipe. In this position each nozzle will cause
the spray to cover the area from the center of the quonset to the opposite
STATE PLANT BOARD
I ■ - :" imigant I from the other end of the noz/
This hos«- m . nough to rea m the ba -
;mmp or U le of tl nl of the building.
I fitf. 1). • ut 65 pounds, is con -d
with run: ns of an drum
front to keep them sliding. I tie uprigh" of 2- by 2-
A gear pun. ngatlOO [x>unds per square u. I deli.
it 2 1/2 gallons of fumigant per minute. H • the use of a small winch
and a wire attached to the sled, the boom spray can be drawn fn
to the front of the quonset at a speed that will deliver the re-
quired dosage uniformly ov< Such an outfit can be constructed
at a nominal cost, is easily ham: .rid will fit into the b< k.
A competent crew should be able to treat a quonset in about 30 minutes.
D -sages of 2 1/2 and 3 gallons of the 80-20 mixture plus 10 percent
nethyl bromide per 1,000 bushels gave very satisfactory results.
■ ■. 80-20 mixture of carbon I Mloride and carbon disulfide at a
dosage of 5 gallons per 1,000 bushels has been .indard tr nt
shelled i orn in steel bins for st i years. ' kills
in out-of-condition corn, scarcity of materials, and the need for
inf< garding dos: - of storage structures led
r study of this mix
111 metal bins the standard dosage of th< mixt.. s satis-
fy if cal Idy sui rain was itment
un) estations of tl tnois grain moth wei In
wooden bins it dosac gallons per
100 bu I: aJ I I ins in: with tl -h. it
- kill this insect In the SUri n. Su:
f f urn igants proved 1 d, but
r 100 squai
i • •
en1 (by volume) of methyl bromi
2 ' mixtu i tra< W
mixtui U< hloride or pi
ed the 1 >oin1 a
: .Ions per 1 .000 1)1.
helfl of tl 20 mixture ph.
: i ,000 bushels U
Other fumigants found to be highly effective for the treatment of
shelled corn in metal bins were a 17-83 mixture of 1,1-dichloro-l -
nitroethane and carbon tetrachloride at 2 gallons and a 10-90 mixture
of bromotrichloromethane and carbon tetrachloride at 3 gallons per
1,000 bushels. The latter mixture did not kill all immature stages of
the rice weevil.
Various mixtures of methyl bromide with ethylene dibromide and
chloropicrin were unsatisfactory under the conditions of these tests.
II I II
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